Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 6 1 2011 03 15 58 63 EN KH Pirali-Kheirabadi Department of Pathobiology, Faculty of Veterinary Medicine, and Research Institute of Zoonotic Diseases, University of Shahrekord, Shahrekord, Iran JA Teixeira da Silva Faculty of Agriculture and Graduate School of Agriculture, Kagawa University, Miki-cho, Ikenobe 2393, Kagawa-ken, Japan 2015 10 03 Background: The aim of this study was to investigate the ‘acaricidal effect' of Zataria multiflora and Ar­temisia annua essential oils on Rhipicephalus (Boophilus) annulatus. Methods: This study was carried out in 2009 in the Laboratory of Parasitology of the Faculty of Veteri­nary Medicine of Shahrekord  University, west central Iran. Six dilutions (5, 10, 20, 40, 60 and 80 µL/cm3) of both essential oils were used against engorged female R. (Boophilus) annula­tus ticks using an in vitro immersion method. The mortality rates for each treatment were re­corded 6, 15 and 24 hours post inoculation (hpi). Mortality rate was analyzed using Repeated Meas­ures Analysis of Variance, and compari­son of means was carried out using General Linear Models Procedure. Results: The mortality rate caused by different dilutions of Z. multiflora essential oil ranged from 26.6% (using 10 µL/cm3) to 100% (using 40 µL/cm3) and for A. annua essential oil it was 33.2 to 100% (using 20 and 80 µL/cm3, respectively) by the end of the experiment (36 hpi). No mortality was recorded for the non-treated control group or for dilutions less than 5 and 10 µL/cm3 using Zataria and Artemisia essential oils, respectively. For Z. multiflora mortality peaked at 15 hpi for all concentrations other than 20 µL/cm3 and took 24 h to achieve its maximum effect while for A. an­nua the two highest concentrations needed 24 hpi to reach their full effect. In addition, essen­tial oils applied at more than 20 and 60 µL/cm3 caused 100% egg-laying failure in engorged fe­male ticks by Zataria and Artemisia, respectively while no failure was observed for the non-treated control group. The mortality rate in both botanical acaricides was dose-dependent. Conclusion: Both these medicinal plants have high potential acaricidal effects on the engorged stage of R. (Boophilus) annulatus in vitro. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/166 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/166/165